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Re: Topband: Fw: 25G insulators

Subject: Re: Topband: Fw: 25G insulators
From: "Donald Chester" <>
Date: Sat, 30 Aug 2003 23:04:44 +0000
List-post: <>

The arc gaps across the insulated section is a simple and very effective way
of taking care of the static charge

It is much better to use ONE insulator to support the tower at a pivot point than to use 3 separate insulators in an insulated section, with the bottom end of the section buried in concrete. The pivot assembly allows the tower to sway slightly under wind conditions and also allows the tower to be adjusted for plumb by simply adjusting the guy wire turnbuckles. The rigid base buried in concrete puts much more stress on the tower in heavy winds. A pivoting tower is likely to survive much higher winds than one with a rigid base.

The best solution would be to find an appropriate size AM broadcast base insulator. I have seen them at the Dayton fleamarket, usually for about $50. New ones are expensive; $500 back in 1980, ??? today. A good homebrew substitute is a large ceramic standoff like the ones used in power substations, about 6" in diameter and about 6" tall. Have a welding shop put together a 1/2 to 3/4" base plate with recepticles to fit the bottoms of the tower section legs, and make up a pier pin assembly to attach to the insulator. Rohn makes a special tapered base section (25TG) for this purpose. When I put up mine in 1980, the TG cost about twice a normal 25G section, but I understand they are far more expensive today.


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